In the tire industry, manufacturers of tires and tire components have endless choices when fabricating such items. For example, the selection of ingredients for the commercial formulations of tires and tire components depends upon the balance of properties desired and the end use. In particular, when fabricating that portion of the tire relied upon for air impermeability such as the tire innerliner, manufacturers have applied a myriad approaches including the widespread use of “butyl” rubbers or elastomers in various embodiments. Butyl rubbers, generally, copolymers of isobutylene and isoprene, optionally halogenated, have widespread application due to their ability to impart desirable air impermeability properties for the tire. For example, due to economic advantages and processing benefits, blends of butyl rubbers with other rubbers such as natural rubbers have been useful.
However, such blends have their limitations. Thus, the tire industry continually seeks improvements to past applications. For example, Exxpro™ elastomers (ExxonMobil Chemical Company, Houston, Tex.), generally, halogenated random copolymers of isobutylene and para-methylstyrene, have been of particular interest due to their improvements over butyl rubbers. Similarly, as with butyl rubbers, due to economics and processing goals, producing a tire or tire components from 100% Exxpro™ elastomers is not the tire industry's ideal application. Therefore, in many cases, a blend of Exxpro™ elastomers with secondary elastomers or other polymers affords a compound having a desirable balance of properties achieved through suitable processing windows. See, e.g., U.S. Pat. Nos. 6,293,327, and 5,386,864, U.S. Patent Application Publication No. 2002/151636, JP 2003170438, and JP 2003192854 (applying various approaches of blends of commercial EXXPRO™ elastomers with other polymers).
Other background references include U.S. Pat. Nos. 5,063,268, 5,391,625, 6,051,653, and 6,624,220, WO 1992/02582, WO 1992/03302, WO 2004/058825, EP 1 331 107 A, and EP 0 922 732 A.
However, due to the rigorous demands of tires and the tire industry's relentless pursuit of a better tire and/or a better process to produce the tire or its respective components, improvements to these blends are also desired. For example, commercial Exxpro™ elastomers, generally having about 5 wt % or about 7 wt % para-methylstyrene based upon the weight of the random copolymer, used alone or in combination with other polymers in blends, still necessitate improvements to the balances of properties for the tire or tire component and/or the process to produce the tire or tire components. Thus, the problem of improving processability of elastomeric compositions useful for tire articles while maintaining or improving the air impermeability and/or other properties of those compositions still remains.